scholarly journals Derivation of Hyperspectral Profile of Extended Pseudo Invariant Calibration Sites (EPICS) for Use in Sensor Calibration

2019 ◽  
Vol 11 (19) ◽  
pp. 2279
Author(s):  
Mahesh Shrestha ◽  
Nahid Hasan ◽  
Larry Leigh ◽  
Dennis Helder
Keyword(s):  
North Africa ◽  
Temporal Stability ◽  
Critical Issue ◽  
Sensor Data ◽  
Sensor Calibration ◽  
Absolute Calibration ◽  
Time Interval ◽  
Calibration Model ◽  
Small Set ◽  
Cross Calibration

Reference of Earth-observing satellite sensor data to a common, consistent radiometric scale is an increasingly critical issue as more of these sensors are launched; such consistency can be achieved through radiometric cross-calibration of the sensors. A common cross-calibration approach uses a small set of regions of interest (ROIs) in established Pseudo-Invariant Calibration Sites (PICS) mainly located throughout North Africa. The number of available cloud-free coincident scene pairs available for these regions limits the usefulness of this approach; furthermore, the temporal stability of most regions throughout North Africa is not known, and limited hyperspectral information exists for these regions. As a result, it takes more time to construct an appropriate cross-calibration dataset. In a previous work, Shrestha et al. presented an analysis identifying 19 distinct “clusters” of spectrally similar surface cover that are widely distributed across North Africa, with the potential to provide near-daily cloud-free imaging for most sensors. This paper proposes a technique to generate a representative hyperspectral profile for these clusters. The technique was used to generate the profile for the cluster containing the largest number of aggregated pixels. The resulting profile was found to have temporal uncertainties within 5% across all the spectral regions. Overall, this technique shows great potential for generation of representative hyperspectral profiles for any North African cluster, which could allow the use of the entire North Africa Saharan region as an extended PICS (EPICS) dataset for sensor cross-calibration. This should result in the increased temporal resolution of cross-calibration datasets and should help to achieve a cross-calibration quality similar to that of individual PICS in a significantly shorter time interval. It also facilitates the development of an EPICS based absolute calibration model, which can improve the accuracy and consistency in simulating any sensor’s top of atmosphere (TOA) reflectance.

scholarly journals Empirical Absolute Calibration Model for Multiple Pseudo-Invariant Calibration Sites

2019 ◽  
Vol 11 (9) ◽  
pp. 1105 ◽  
Author(s):  
Bipin Raut ◽  
Morakot Kaewmanee ◽  
Amit Angal ◽  
Xiaoxiong Xiong ◽  
Dennis Helder
Keyword(s):  
Region Of Interest ◽  
Image Data ◽  
Sensor Calibration ◽  
Absolute Calibration ◽  
Landsat 8 ◽  
Calibration Model ◽  
General Applicability ◽  
Landsat 7 ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Sentinel 2A

This work extends an empirical absolute calibration model initially developed for the Libya 4 Pseudo-Invariant Calibration Site (PICS) to five additional Saharan Desert PICS (Egypt 1, Libya 1, Niger 1, Niger 2, and Sudan 1), and demonstrates the efficacy of the resulting models at predicting sensor top-of-atmosphere (TOA) reflectance. It attempts to generate absolute calibration models for these PICS that have an accuracy and precision comparable to or better than the current Libya 4 model, with the intent of providing additional opportunities for sensor calibration. In addition, this work attempts to validate the general applicability of the model to other sites. The method uses Terra Moderate Resolution Imaging Spectroradiometer (MODIS) as the reference radiometer and Earth Observing-1 (EO-1) Hyperion image data to provide a representative hyperspectral reflectance profile of the PICS. Data from a region of interest (ROI) in an “optimal region” of 3% temporal, spatial, and spectral stability within the PICS are used for developing the model. The developed models were used to simulate observations of the Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+), Landsat 8 (L8) Operational Land Imager (OLI), Sentinel 2A (S2A) MultiSpectral Instrument (MSI) and Sentinel 2B (S2B) MultiSpectral Instrument (MSI) from their respective launch date through 2018. The models developed for the Egypt 1, Libya 1 and Sudan 1 PICS have an estimated accuracy of approximately 3% and precision of approximately 2% for the sensors used in the study, comparable to the current Libya 4 model. The models developed for the Niger 1 and Niger 2 sites are significantly less accurate with similar precision.

scholarly journals TEMPORAL STABILITY OF TUZ GÖLÜ AND ATACAMA DESERT REFERENCE SURFACES FOR ABSOLUTE CALIBRATION OF ORBITAL SENSORS

2015 ◽  
Vol 33 (2) ◽  
Author(s):  
Cibele Teixeira Pinto ◽  
Flávio Jorge Ponzoni ◽  
Ruy Morgado Castro
Keyword(s):  
Optical Sensors ◽  
Temporal Stability ◽  
Atacama Desert ◽  
Temporal Analysis ◽  
Earth Observation ◽  
Sensor Calibration ◽  
Absolute Calibration ◽  
Radiometric Calibration ◽  
Definition Of ◽  
Better Than

ABSTRACT. The vicarious absolute calibration of electro-optical sensors dedicated to the Earth observation includes the definition of a reference surface from which radiometric measurements taken from the ground are compared to the effective radiance measured by the sensor in orbit. In order to facilitate the surface radiometric characterization process and consequently the sensor radiometric calibration, it is desirable that the surface presents, besides additional characteristics, temporal reflectance stability. This study aimed to evaluate the temporal stability of two potential reference surfaces for radiometric calibration of orbital electro-optical sensors located at: Tuz Gölü Salar in Turkey and Atacama Desert in Chile. Therefore, a temporal analysis of the radiometric properties of these two surfaces using cloud free images of TM/Landsat 5 sensor, acquired from 2003 to 2011, was performed. It was concluded, based on statistical criteria, that both reference surfaces do not presented temporal stability. Nevertheless, both surfaces may still be used for sensor calibration purposes if they were submitted to further spectral characterization with higher frequency and/or if the surfaces were considered stable “enough” within a certain limit of variation in reflectance. Taking that into account, according to the results of this work, it can be stated that Tuz G¨ol¨u surface reflectance has temporal stability within a range of 3-14% and the Atacama Desert better than 6%.Keywords: Earth observation sensors, radiometric calibration, reflectance, TM/Landsat 5.RESUMO. A primeira etapa para a realização da calibração absoluta de sensores de observação da Terra é a definição de uma superfície de referência. Um dos métodos mais comuns de calibração após o lançamento do sensor utiliza medições radiométricas de áreas localizadas na superfície terrestre. Para facilitar o processode caracterização da superfície e consequentemente o processo de calibração radiométrica, é desejável que a superfície apresente, entre outras características, estabilidade temporal. Assim, este trabalho teve como objetivo avaliar a estabilidade temporal de duas superfícies de referência potenciais para a calibração radiométrica de sistemas sensores eletro-ópticos: o salar de Tuz Gölü na Turquia e o deserto de Atacama no Chile. Para tanto, foi realizada uma análise temporal do comportamento espectral das duas superfícies por meio de imagens do sensor TMabordo do Landsat 5 livres de nuvens adquiridas nos anos de 2003 a 2011.De acordo com os resultados obtidos foi possível concluir, segundo os critérios estatísticos, que as duas superfícies de referência não apresentam estabilidade temporal. Apesar disso, as duas superfícies ainda podem ser utilizadas para calibração de sensores. Nesse caso, deve-se caracterizar espectralmente as duas áreas com maior frequência e/ou considerar a superfície como sendo “suficientemente” estável se a variação na reflectância ao longo do tempo for menor do que um determinado valor. Se esta consideração for feita pode-se afirmar, segundo o resultado desse trabalho, que Tuz Gölü tem estabilidade temporal entre 3 a 14% e o deserto de Atacama melhor do que 6%.Palavras-chave: sensores de observação da Terra, calibração radiométrica, reflectância, TM/Landsat 5.

scholarly journals Cross-calibration of S-NPP VIIRS moderate-resolution reflective solar bands against MODIS Aqua over dark water scenes

2017 ◽  
Vol 10 (4) ◽  
pp. 1425-1444 ◽  
Author(s):  
Andrew M. Sayer ◽  
N. Christina Hsu ◽  
Corey Bettenhausen ◽  
Robert E. Holz ◽  
Jaehwa Lee ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
Spectral Response ◽  
Total Error ◽  
Visible Spectral Region ◽  
Sensor Data ◽  
Absolute Calibration ◽  
Modis Aod ◽  
Data Products ◽  
Moderate Resolution ◽  
Cross Calibration

Abstract. The Visible Infrared Imaging Radiometer Suite (VIIRS) is being used to continue the record of Earth Science observations and data products produced routinely from National Aeronautics and Space Administration (NASA) Moderate Resolution Imaging Spectroradiometer (MODIS) measurements. However, the absolute calibration of VIIRS's reflected solar bands is thought to be biased, leading to offsets in derived data products such as aerosol optical depth (AOD) as compared to when similar algorithms are applied to different sensors. This study presents a cross-calibration of these VIIRS bands against MODIS Aqua over dark water scenes, finding corrections to the NASA VIIRS Level 1 (version 2) reflectances between approximately +1 and −7 % (dependent on band) are needed to bring the two into alignment (after accounting for expected differences resulting from different band spectral response functions), and indications of relative trending of up to  ∼  0.35 % per year in some bands. The derived calibration gain corrections are also applied to the VIIRS reflectance and then used in an AOD retrieval, and they are shown to decrease the bias and total error in AOD across the mid-visible spectral region compared to the standard VIIRS NASA reflectance calibration. The resulting AOD bias characteristics are similar to those of NASA MODIS AOD data products, which is encouraging in terms of multi-sensor data continuity.

scholarly journals A Novel Deep Learning Approach for Machinery Prognostics Based on Time Windows

2019 ◽  
Vol 9 (22) ◽  
pp. 4813 ◽  
Author(s):  
Hanbo Yang ◽  
Fei Zhao ◽  
Gedong Jiang ◽  
Zheng Sun ◽  
Xuesong Mei
Keyword(s):  
Time Windows ◽  
Remaining Useful Life ◽  
Sensor Data ◽  
Time Interval ◽  
Kernel Module ◽  
Initial Stage ◽  
Research Task ◽  
Consecutive Time ◽  
Useful Life

Remaining useful life (RUL) prediction is a challenging research task in prognostics and receives extensive attention from academia to industry. This paper proposes a novel deep convolutional neural network (CNN) for RUL prediction. Unlike health indicator-based methods which require the long-term tracking of sensor data from the initial stage, the proposed network aims to utilize data from consecutive time samples at any time interval for RUL prediction. Additionally, a new kernel module for prognostics is designed where the kernels are selected automatically, which can further enhance the feature extraction ability of the network. The effectiveness of the proposed network is validated using the C-MAPSS dataset for aircraft engines provided by NASA. Compared with the state-of-the-art results on the same dataset, the prediction results demonstrate the superiority of the proposed network.

scholarly journals Longitudinal study of fingerprint recognition

2015 ◽  
Vol 112 (28) ◽  
pp. 8555-8560 ◽  
Author(s):  
Soweon Yoon ◽  
Anil K. Jain
Keyword(s):  
Statistical Models ◽  
Recognition Accuracy ◽  
Temporal Stability ◽  
Poor Quality ◽  
Time Span ◽  
Fingerprint Recognition ◽  
Time Interval ◽  
General Belief ◽  
Probability Of Error ◽  
Fingerprint Database

Human identification by fingerprints is based on the fundamental premise that ridge patterns from distinct fingers are different (uniqueness) and a fingerprint pattern does not change over time (persistence). Although the uniqueness of fingerprints has been investigated by developing statistical models to estimate the probability of error in comparing two random samples of fingerprints, the persistence of fingerprints has remained a general belief based on only a few case studies. In this study, fingerprint match (similarity) scores are analyzed by multilevel statistical models with covariates such as time interval between two fingerprints in comparison, subject’s age, and fingerprint image quality. Longitudinal fingerprint records of 15,597 subjects are sampled from an operational fingerprint database such that each individual has at least five 10-print records over a minimum time span of 5 y. In regard to the persistence of fingerprints, the longitudinal analysis on a single (right index) finger demonstrates that (i) genuine match scores tend to significantly decrease when time interval between two fingerprints in comparison increases, whereas the change in impostor match scores is negligible; and (ii) fingerprint recognition accuracy at operational settings, nevertheless, tends to be stable as the time interval increases up to 12 y, the maximum time span in the dataset. However, the uncertainty of temporal stability of fingerprint recognition accuracy becomes substantially large if either of the two fingerprints being compared is of poor quality. The conclusions drawn from 10-finger fusion analysis coincide with the conclusions from single-finger analysis.

scholarly journals Practical example for use of the supervised vicarious calibration (SVC) method on multisource hyperspectral imagery data – ValCalHyp airborne hyperspectral campaign under the EUFAR framework

2014 ◽  
Vol XL-7 ◽  
pp. 51-53
Author(s):  
A. Brook ◽  
E. Ben Dor
Keyword(s):  
Atmospheric Correction ◽  
Ground Truth ◽  
Critical Issue ◽  
Radiometric Calibration ◽  
Vicarious Calibration ◽  
Flight Direction ◽  
Novel Approach ◽  
Novel Method ◽  
General Goal ◽  
Cross Calibration

A novel approach for radiometric calibration and atmospheric correction of airborne hyperspectral (HRS) data, termed supervised vicarious calibration (SVC) was proposed by Brook and Ben-Dor in 2010. The present study was aimed at validating this SVC approach by simultaneously using several different airborne HSR sensors that acquired HSR data over several selected sites at the same time. The general goal of this study was to apply a cross-calibration approach to examine the capability and stability of the SVC method and to examine its validity. This paper reports the result of the multi sensors campaign took place over Salon de Provenance, France on behalf of the ValCalHyp project took place in 2011. The SVC method enabled the rectification of the radiometric drift of each sensor and improves their performance significantly. The flight direction of the SVC targets was found to be a critical issue for such correction and recommendations have been set for future utilization of this novel method. The results of the SVC method were examined by comparing ground-truth spectra of several selected validation targets with the image spectra as well as by comparing the classified water quality images generated from all sensors over selected water bodies.

scholarly journals A Smart WiFi Multi-Sensor Node for Fire Detection Mechanism Based on Social Network

2018 ◽  
Vol 14 (10) ◽  
pp. 4
Author(s):  
Anekwong Yoddumnern ◽  
Roungsan Chaisricharoen ◽  
Thongchai Yooyativong
Keyword(s):  
Sensor Node ◽  
Finite Impulse Response ◽  
Fire Detection ◽  
Sensor Data ◽  
Sensor Calibration ◽  
Sensing Element ◽  
Detection Mechanism ◽  
Small Device ◽  
Home Area ◽  
Calibration Time

<p class="0abstract">A small device with WiFi multi-sensing element is very important under a social digital century<strong>.</strong> This study aims to implement the hardware and the power of the algorithm with WiFi technologies. Especially, the multi-sensors have to reinforce around a home area and support to any requirement in the term of digital society. This study focus to care the home security— on going to the fire detection with applying several technologies based on a Cloud. Firstly, the multi-sensor calibration has used calibration time and self-calibration as the Finite Impulse Response (FIR). Next, the Full-Scale Kalman Filter (FSKF) helps to fill data and estimate the accuracy data. After that, the fire detection mechanism has used Fuzzy logic to detect and send alert messages over an IFTTT process. There are changed following event-- the data range of fire proportion inside the home. Furthermore, The OFF-Mode has reduced the power consumption suddenly the WiFi module is sent the sensor data to the Cloud. Finally, the WiFi multi-sensor node will use more than one sensor as the same detector will be a high stability and high accuracy.</p>

scholarly journals Observations and Recommendations for Coordinated Calibration Activities of Government and Commercial Optical Satellite Systems

2020 ◽  
Vol 12 (15) ◽  
pp. 2468 ◽  
Author(s):  
Dennis Helder ◽  
Cody Anderson ◽  
Keith Beckett ◽  
Rasmus Houborg ◽  
Ignacio Zuleta ◽  
...  
Keyword(s):  
Optical Systems ◽  
Sensor Calibration ◽  
Optical Remote Sensing ◽  
Coordinated Development ◽  
Data Interoperability ◽  
Team Members ◽  
Satellite Systems ◽  
The Earth ◽  
All Optical ◽  
Cross Calibration

One of the biggest changes in the world of optical remote sensing over the last several years is the sheer increase in the number of sensors that are imaging the Earth in moderate to high spatial resolution. With respect to the calibration of these sensors, they are broadly classified into two types, namely government systems and commercial systems. Because of the differences in the design and mission of these sensor types, calibration approaches are often substantially different. Thus, an opportunity exists to foster discussion between calibration teams for these sensors with the goal of improving overall sensor calibration and data interoperability. The approach used to accomplish this task was a one-day workshop where team members from both government and commercial sensors could share best practices, discuss methods for collaboration and improvement, and make recommendations for continuing activities. Five major recommendations were developed from the event that focused on coordinated activities using pseudo invariant calibration sites (PICS), broader and more consistent communication, collaboration on specific cross-calibration opportunities, developing a reference sensor for all optical systems, and encouraging the coordinated development of surface reflectance products. Workshop participants concluded that regular interactions between these teams could foster a better calibration of all sensor systems and accelerate the improved interoperability of surface products.

scholarly journals Transforming Unmanned Aerial Vehicle (UAV) and Multispectral Sensor into a Practical Decision Support System for Precision Nitrogen Management in Corn

2020 ◽  
Vol 12 (10) ◽  
pp. 1597
Author(s):  
Laura J. Thompson ◽  
Laila A. Puntel
Keyword(s):  
Decision Support ◽  
High Resolution ◽  
Decision Support System ◽  
Support System ◽  
Critical Issue ◽  
N Fertilization ◽  
Sensor Data ◽  
N Application ◽  
High Resolution Imagery ◽  
N Management

Determining the optimal nitrogen (N) rate in corn remains a critical issue, mainly due to unaccounted spatial (e.g., soil properties) and temporal (e.g., weather) variability. Unmanned aerial vehicles (UAVs) equipped with multispectral sensors may provide opportunities to improve N management by the timely informing of spatially variable, in-season N applications. Here, we developed a practical decision support system (DSS) to translate spatial field characteristics and normalized difference red edge (NDRE) values into an in-season N application recommendation. On-farm strip-trials were established at three sites over two years to compare farmer’s traditional N management to a split-application N management guided by our UAV sensor-based DSS. The proposed systems increased nitrogen use efficiency 18.3 ± 6.1 kg grain kg N−1 by reducing N rates by 31 ± 6.3 kg N ha−1 with no yield differences compared to the farmers’ traditional management. We identify five avenues for further improvement of the proposed DSS: definition of the initial base N rate, estimation of inputs for sensor algorithms, management zone delineation, high-resolution image normalization approach, and the threshold for triggering N application. Two virtual reference (VR) methods were compared with the high N (HN) reference strip method for normalizing high-resolution sensor data. The VR methods resulted in significantly lower sufficiency index values than those generated by the HN reference, resulting in N fertilization recommendations that were 31.4 ± 10.3 kg ha−1 higher than the HN reference N fertilization recommendation. The use of small HN reference blocks in contrasting management zones may be more appropriate to translate field-scale, high-resolution imagery into in-season N recommendations. In view of a growing interest in using UAVs in commercial fields and the need to improve crop NUE, further work is needed to refine approaches for translating imagery into in-season N recommendations.

scholarly journals Validation of a nutrition knowledge questionnaire in Italian students attending the University of Parma

2020 ◽  
Vol 23 (9) ◽  
pp. 1527-1531 ◽  
Author(s):  
Alice Rosi ◽  
Daniela Martini ◽  
Giuseppe Grosso ◽  
Maria Laura Bonaccio ◽  
Francesca Scazzina ◽  
...  
Keyword(s):  
University Students ◽  
Temporal Stability ◽  
Internal Consistency Reliability ◽  
Nutrition Knowledge ◽  
Time Interval ◽  
Validity And Reliability ◽  
Nutritional Recommendations ◽  
Knowledge Questionnaire ◽  
Good Ability ◽  
The University

AbstractObjective:The aim of this study was to assess the validity and reliability of a self-administered nutrition knowledge (NK) questionnaire for Italian university students.Design:The NK questionnaire included ninety questions on experts’ nutritional recommendations, nutritional content of food, health aspects of food and diets, relationship between diet and diseases, and proper food choices. It was administered to the same population under the same conditions on two different occasions with a time interval of 3 weeks between the two administrations.Setting:The survey was carried out at the University of Parma (Italy) during the 2018–2019 academic year.Participants:Data were collected for 132 bachelor and master degree students attending the University of Parma, either attending or not nutrition classes during their studies (19–30 years, 29·5 % males, 57·6 % with an academic nutrition background).Results:The questionnaire revealed high overall internal consistency reliability (Cronbach’s α > 0·8) and a good temporal stability with high correlation of the total score (r = 0·835, P < 0·001). Moreover, it showed a good ability to discriminate between subjects with potentially different NK.Conclusions:This NK questionnaire proved to be a reliable, valid and easy-to-use tool for assessing the NK of Italian university students, either with or without nutrition background.

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